Short-circuiting device



June 12, 1923. 1,458,682

H. L. BRUMP SHORT CIRCUITING DEVICE Filed April 4. 1922 2 Sheets-Sheet 1 WIINESSES; INVEN 5% im W 1/; ATTORNEY Patented June 12, 1923.

UNITED STATES 1,458,682 PATENT OFFICE.

HERBERT L. BRUHP, OF DAYTON, OHIO, ASSIGNOR TO THE DAYTON FAN & MOTOR COMPANY, OF DAYTON, OHIO, A CORPORATION OF OHIO.

SHORT-CIRCUI'I'IN G DEVICE.

Application med April 4,

To all whom it may concern:

Be it known that I, Hammer L. B ntm r, a citizen of the United States, resldin 1n the city of Dayton, in the county of out gomery and State of Ohio, have invented certain new and useful Improvements in Short-Circuiting Devices, of which the following is a s cification.

My invention relates primarily, though not exclusively, to certain alternating current motors, known to the trade as repulsion induction motors, which are designed to start as repulsion motors having series motor characteristics When they approach the speed at which an alternating current induction motor would normally function, the armature windings are short-circuited, after which the short-circuited armature acts as the squirrel cage rotor of an induction motor. r

The primary object of m therefore, is to provide a simp and 0500- tive device for short circuitin the armature windings of repulsion in uction motors after they have attained the speed at which alternatingicurrent induction motors normally function. The invention may also invention,

be employed whereever it is desired to use a ccntrifugally impelled, flexible element for performing a mechanical or an electrical function.

The invention comprises a coil spring which surrounds a number of suitable weights that are constrained, by suitable means, to turn with the armature shaft, and are so mounted as to move outwardly by centrifugal force as the speed 'of the armature increases. As the weights move outwardly, the coil spring is ex ended by them to form contact between t e ends of the commutator bars and a copper shell or retainer to short circuit the armature windings so that the armature will function as the s uirrel cage rotor of an induction motor. en the speed of the device decreases, the coil spring which forms the contact member will contract to return and hold the weights in their inner positions, as when the device is being started or is at rest.

Many possible variations in the construction and arrangement of the device will be apparent. The spring which effects the con tact may take the form other than that of a round cross section, or it might be formed complished by -Figure 2 is a side 1922. Serial No. 549,572.

of a series of suitable punchings. Furthermore-the spring, however formed, may be used only as a. contact member,the return and the retention of the weights being acother means such as a smaller spring within the large contact spring. Basically, the invention comprises a centrifugal device in which a number of suitabl restrained weights are adapted to estab ish, through a flexible element a con tact short circuiting the bars of; t e commutator as the wei hts are thrown outwardly bycentrifugafi force.

In the drawin illustratin my invention and the various modifications thereof, Figure 1 is. an end elevation of my short circuiting device, with the shell partly broken away to show the contact spring and weights in their short circuiting' position.

elevation, partly in section, of the device when short circuiting the armature windings. Fi re'3 is an end elevation of the device wlth the shell partly broken away to show the contact spring and weights when the armature is at rest. Figure 4 is a side elevation, partly in section, of said device when the armature is at rest. Figure 5 is a perspective view of one of the centrifugal weights. Figure 6 is a cross sectiona view of a modified form of my improved short circuitin device, showing a tension spring within t e contact spring. And F i re 7is an end elevation of the modifi form of said device, with the shell partly broken away to reveal the inner and outer sprin Throughout the specification and drawings, similar reference characters denote corresponding parts.

In the drawings, the numeral 1 designates an armature shaft upon which is secured a commutator spider 2. Secured to the latter in the conventional manner is a circumferential series of commutator bars 3 of uniform length. (See Figures 2 and 4.)

Fast on the shaft 1 a short distance in front of the commutator just described, is a hub 4 whose inner ripheral portion is formed to provide a edge 5 to receive the o n central part of a cup-she disc 6. T l latter is tightly fitted on t e annular ledge portion 5 of the hub 4 to turn with the latter when the armature shaft 1 is rotated.

The outer annular edge of the inwardly turned flanged rim of the disc 6 is but a short distance from the inwardly tapering end portions of the commutator bars 3, to permit a coil spring 7, preferably constructed of phosphor bronze, to make contact with both the disc and the commutator bars for the purpose of short circuiting the latter when the spring is expanded by the centrifugal means now to be described.

Turned inwardly from the cup-shaped disc 6, a short distance from the hub is a series of ually-spaced flat driving lugs 8. Each of t ese lugs is adapted to project loosely into a radial groove 9 provided in the middle ortion of a se mental weight 10, preferabi; constructed 0 steel, whereby these weights ma be mounted between the cupped disc 6 and the commutator s ider 2 for a free outward movement along t e lugs 8 when the armature shaft 1 is rotated. (See Figures \1, 2 and 5.)

The outer eriphery of'each oueof the segmental weights 10 is concaved receive a respective part of the inner periphery of the coil spring 7, which acts as a retaining member to hold the weights against the armature shaft 1 when the latter is at rest. When the rotation of the armature shaft is started, these weights 10, being free to slide outwardly along the lugs 8, will act as centrifugal elements to press the spring 7 outwardly, as the speed of the device increases, until the said spring contacts, with the outer edge portion of the cupped disc 6 and the opposite ends of the commutator bars 3 to short circuit the latter. At this point the short circuited armature will function as the squirrel ea c rotor of an induction motor, but up to't e time the commutator bars are short circuited by the spring 7, the device will start as a repulsion motor having series characteristics.

From the above descri tion it will be seen that the spring 7 not on y acts as a contact member, but as a retaining element for the segmental weights when the device is starting or is at rest In Figures 6 and 7 I have shown a modified short circuiting device in which I place a small garter spring 11 within the large spring 7, to act as a retaining element for the weights, leaving the spring 7 free to function only as the contact member. This, among other thin enables the outer spring to be constructe of a material of great conductivity at the sacrifice of extreme flexibility, since the contraction of the spring is assisted by the inner spring 11, to

turned driving lu moses:

retain the weights 10 in their inner positions.

From the foregoing description it will be seen that I have rovided a simple and effective short circuiting device in which a number of suitabl restrained weights are adapted to establish, through a flexible memher, a contact which short circuits the bars of the commutator of a repulsion induction motor as the weights are thrown outwardly by centrifugal force when the speed of the motor approaches that at which an alternating current induction motor wouldnormally function.

I do not Wish to be limited to the details of construction and arrangement herein shown and described, and any changes or modifications may be made therein within the scope of the subjoined claims.

Having described my invention, I claim:

1. In an alternating current motor, an armature shaft, a commutator mounted thereon, a cup-shaped disc mounted on said shaft to face the commutator, guiding projections on said disc, centrifugal weights mounted between the disc and commutator and free to move outwardly along said pro- 'ections, and a flexible element adapted to be moved outwardly by the centrifugal weights, when the armature shaft attains a certain speed, to make contact between the rim portion of the cup-shaped disc and the commutator for the purpose of short circuitin the latter.

2. 11 an alternating current motor, an armature shaft, a commutator mounted thereon, a cup-shaped disc mounted on said shaft to face the commutator, inwardlyon said disc, segmental weights mounted etween the disc and the commutator, each weight having a central radial groove adapted to receive a driving lug and free to be moved outwardly along it by centrifugal force, said weights also having concaved outer peripheries, and a garter spring fitted in the concaved periphcries of the weights and adapted to be moved outwardly by the latter when the armature shaft attains a certain speed, to make contact between the rim portion of the cupshaped disc and the commutator for the purpose of short circuiting the latter.

In testimony whereof I have hereunto set my hand this 21st day of March, 1922.

HERBERT L. BRUMP. Witness:

Howaao S. Sun-n. 

